how to replace the element with random number based if statement

4 次查看(过去 30 天)
Helllo everyone
i have a problem to change element of array with iteration approach. refer to https://www.mathworks.com/matlabcentral/answers/8817-how-to-replace-the-elements-of-a-matrix-using-the-conditions-if-else , i have same problem but little different. for instance i have mut1 = [.11 .12 .13 .14 .15 .16 .17 .18 .19 .20] and constan number 0.5. i want to replace element of mut1 with 'random number between' if random number(rmi) < 0.5. so this is what iam doing.
mutC = zeros(size(mut1));
pm = 0.5;
for i = 1:numel(mut1)
rmi = rand(1,1)
rCm = rbC+(raC-rbC).*rand(1,1)
if rmi<pm
mutC = rCm
else
mutC = mut1
end
end
but the final result is always mutC = mut1. there is no number from rCm.
I will appreciate any help. thank you.

采纳的回答

Andrei Bobrov
Andrei Bobrov 2019-10-16
编辑:Andrei Bobrov 2019-10-16
mutC = mut1;
[m,n] = size(mut1);
pm = 0.5;
rmi = rand(m,n);
rCm = rbC+(raC-rbC).*rand(m,n);
for i = 1:numel(mut1)
if rmi(i) < pm
mutC(i) = rCm(i);
end
end
or
pm = .5;
mutC = mut1;
[m,n] = size(mut1);
rCm = rbC+(raC-rbC).*rand(m,n);
lo = rand(m,n) < pm;
mutC(lo) = rCm(lo);
  3 个评论

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更多回答(1 个)

sid Chen
sid Chen 2019-10-16
Andrei Answer is very clear.
The problem is
if rmi<pm
mutC = rCm
else
mutC = mut1
with these code, you replace the whole matrix, all the elements are replaced.
To avoid this, you need to replace only one elements step by step. Just add an subscipt 'i' to point the element to be repalced.
if rmi<pm
mutC(i) = rCm(i)
else
mutC(i) = mut1(i)
  2 个评论
Genz
Genz 2019-10-16
when i run this code become error "index exceeds matrix dimensions"
sid Chen
sid Chen 2019-10-17
if rmi<pm
mutC(i) = rCm % change here, rCm is a number,not a matrix
else
mutC(i) = mut1(i)

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